6.5.1 Hearing Disorders

Question 1

What is the Weber test?

Answer 1

Weber– place tuning fork in center of head

• Normal: sound equal in both ears
• Sensorineural Loss: sound louder in normal ear
• Conductive Loss: sound louder in affected ear

Question 2

What are the characteristics of audiograms and how are they plotted?

Answer 2

-Plotted with Frequency on X axis and decibels (loudness) on Y axis

-Thresholds are plotted relative to average normal threshold at each frequency

Question 3

Describe an audiogram for a patient with normal hearing.

Answer 3

Question 4

How are babies or uncooperative patients tested for hearing?

Answer 4

Objective testing

• Auditory Brainstem Response (ABR): evoked potential measured from scalp
• Otoacoustic Emissions (DPOAE): recorded from small microphone in ear canal. Measure of Outer Hair Cell function (cochlear function)

Question 5

What is the difference between hearing aids and cochlear implants?

Answer 5

Question 6

What type of damage can otitis media cause?

Answer 6

Sensorineural hearing loss

If long standing (inner ear damage)

Question 7

What is auditory brainstem response?

Answer 7

Question 8

What is the Rinne Test?

Answer 8

Rinne – tuning fork placed on mastoid process (bone cond) and then in front of ear (air cond)

• Normal: will hear sound when fork is moved outside ear, after vibrations stop on bone
• Sensorineural Loss: will hear sound breifly on bone, but will with air (+ Result)
• Conductive Loss: won’t hear sound when fork outside ear (- Result)

Question 9

What is CGF166 Gene Therapy?

Answer 9

Question 10

What is air conduction vs bone conduction?

Answer 10

Air conduction: normal route by which airborne sound reaches cochlea - Hearing loss indicates conductive or sensorineural loss

Bone conduction: vibrating probe is applied to skull; vibrations are transmitted directly to cochlea, bypassing the middle ear - hearing loss indicates ONLY sensorineural loss

Question 11

What is sensorineural hearing loss?

Answer 11

-pathology of inner ear (sensory/cochlea) or CN VIII (neural)

Question 12

What is Meniere’s Disease?

Answer 12

-Idiopathic endolymphatic hydrops

• Overproduction or inadequate turnover of endolymph
• Puts excess pressure on hair cells
• Symptoms are fluctuating – hearing loss, vertigo, tinnitis, aural fullness
• Long term pressure has potential to cause permanent hearing loss
• Treatment: low salt diet

Question 13

What are some common causes of conductive hearing loss?

Answer 13

Question 14

How will you determine whether a patient has conductive or sensorineural hearing loss?

Answer 14

-accomplished by comparison of air and bone conduction thresholds

Question 15

How is hearing measured in adults?

Answer 15

Subjective testing

• Present tones separately to each ear in a soundproof both
• Vary frequency and intensity

-Determine threshold as a function of frequency

-Determine ability to discriminate speech sounds

Question 16

What is otoacoustic emissions?

Answer 16

Question 17

What are the major classes of ototoxic drugs?

Answer 17

These cause damage to inner ear hair cells

Asprin

Aminoglycoside antibiotics

Loop diuretics

Cisplatin

Quinine

Question 18

What is hearing level?

Answer 18

dB HL = Measured threshold for individual - normal threshold

Question 19

What is a speech banana?

Answer 19

frequency and HL range important for speech perception (discrimination)

Question 20

What are some causes of sensorineural hearing loss?

Answer 20

Question 21

What is the advantage of an audiogram over frequency theshold curves?

Answer 21

Hearing thresholds vary by frequency

Question 22

What is Central hearing loss?

Answer 22

CNS damage; relatively uncommon

Question 23

What is a conductive hearing loss?

Answer 23

-impaired conduction of sound through external/middle ear to inner ear

Question 24

How would an audiogram look for a patient with mixed conductive and sensorineural loss look?

Answer 24

Mixed Loss

• -Bone: increased threshold
• -Air: increased threshold
• -Problem: ext/middle AND inner ear

Question 25

What is important with children and hearing disorders?

Answer 25

Early diagnosis and intervention is critical

Learning disabilities

Delayed emotional and personality development

Question 26

What is Tinnitus? Explain Objective vs Subjective.

Answer 26

• Perception of phantom sound that occurs in absence of actual sound (Ringing)
• Often accompanies cochlear hair cell loss (ex: caused by noise damage)
• Objective Tinnitus: true sound produced by pulsation of blood vessel
• Subjective Tinnitus: phantom sound produced by dysfunction in auditory system
• Because it is typically of CNS origin, cutting CN VIII will produce no relief

Question 27

Hearing thresholds vary by? What range of frequencies can humans hear over?

Answer 27

Frequency

Humans can hear between the ranges of 20-20,000Hz.

Question 28

How would an audiogram of a patient with conductive hearing loss compare to sensorineural loss?

Answer 28

Conductive Loss

• Bone: normal
• Air: increased threshold
• Problem: ext/middle ear

Sensorineural Loss

• Bone: increased threshold
• Air: increased threshold
• Problem: inner ear

Question 29

What is Presbycusis?

Answer 29

Aging

High Frequency hair cells are harmed first

Question 30

Can you describe the characteristics of outer vs inner hair cell loss?

Answer 30

OHCs are more vulnerable than IHCs to damage

Cochlea may have completely normal IHCs, but lack OHCs

IHCs are sensory transducers: loss of IHCs = deafness

OHCs are amplifiers: loss of OHCs = 30-40dB hearing loss